After-fabrication hot-dip galvanizing involves dipping ferrous articles in a bath of molten zinc (Zn). Upon removal of the article from the bath the excess Zn runs off of the article back into the bath. The drainage of the Zn plays a critical role in the surface finish of the galvanized article. Poor drainage will cause Zn to accumulate in angles and corners of the article. Zn will also accumulate in holes, grooves and channels present on the article to be galvanized. Poor drainage is also characterised by icicles which form on edges as the article is removed from the galvanizing bath.
Zinc used for after-fabrication hot-dip galvanizing is saturated in iron (Fe) (.about.300 ppm). Small amounts of aluminum (Al) (.about.20 to 70 ppm) are sometimes added to increase the brightness of the coating. Presently the drainage of Zn used for after-fabrication hot-dip galvanizing is increased through the addition of lead (Pb) up to the solubility limit at the galvanizing temperature being used (.about.1.4 wt % Pb at 460.degree. C.). These levels of Al, Fe and Pb describe a conventional Pb-containing Zn alloy used for after-fabrication hot-dip galvanizing.